Older, mechanically ventilated survivors of critical illness are frail and functionally impaired. These deficiencies are a result of critical illness itelf, chronic comorbidities, prolonged bed rest during their acute ICU stay, and their continued care at long term acute care facilities. This leads to inflammation, sarcopenia, malnutrition, chronic anemia and worsening fatigue, weakness and disability. Often, physical rehabilitation is de-escalated in the long term acute care hospital (LTACH) rather than advanced due to these older patients' frailty, multiple comorbidities, chronic disability, impaired mobility, cognitive dysfunction, as well as limited resources. This results in regression of any functional or physical gains achieved in the medical center. We propose a pilot study trialing an 8-week multimodal rehabilitation program (MRP) for older survivors of critical illness who require prolonged mechanical ventilation in a LTACH. This pilot study tests the hypothesis that an MRP that targets functional mobility, strength, endurance and motivation will improve mobility function (gait and balance), and basic activities of daily living (ADLs), by increasing strength and ambulatory capacity and reducing inflammation more than usual rehabilitation care in these patients. The goal is to show that the physical and functional gains made by these older patients enrolled in our MRP will translate into clinically meaningful outcomes, including increased ambulatory capacity, respiratory muscle strength, improved quality of life and better rates of weaning from mechanical ventilation.